[virthost-full-cleanup] use 'become' instead of 'sudo'

- This patch avoids deprecations warning about using sudo/sudo_user
  instead of become/become_user.

Change-Id: I1f4909cd25ffbe3d53dd55118fe1af0052cf6b9a
Signed-off-by: Gael Chamoulaud <gchamoul@redhat.com>

roles/virthost-full-cleanup/tasks/main.yml

@@ -50,7 +50,7 @@
       command: virsh net-destroy default
 
     - name: destroy default pool
-      sudo: yes
+      become: yes
       command: virsh pool-destroy default
 
     - name: destroy local libvirt storage, networks and config